U.S. Severe Weather Forecast (Coup d'œil sur la convection)

Day Three

acus01 kwns 240549 
Storm Prediction Center ac 240547 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1247 am CDT sun may 24 2015 

Valid 241200z - 251200z 

..there is a slight risk of severe thunderstorms this afternoon and evening 
across parts of the southeastern plains and Ozark Plateau into 
portions of the middle/lower Mississippi Valley... 

..there is a marginal risk of severe thunderstorms across surrounding areas of the 
Mississippi Valley...and portions of the central and Southern 

Severe thunderstorms are possible today across the southeastern 
plains and Ozark Plateau into portions of the middle and lower 
Mississippi Valley. Other more widely scattered strong to severe 
storms are possible across parts of the central and Southern Plains. 

Models indicate that a subtropical high centered near South Atlantic 
coastal areas will remain prominent through this forecast period. 
However...a ridge axis extending to its northwest appears likely to 
shift east of the Mississippi Valley...as the bulk of broader scale 
troughing within one branch of the split middle-latitude westerlies 
begins to gradually progress east of the intermountain west. 

This latter feature is comprised of a number of smaller scale 
perturbations...some of which are already supporting considerable 
thunderstorm activity across the central and Southern Plains...where 
a return flow of seasonably high moisture content is ongoing around 
the western periphery of the subtropical ridge. This 
moisture...characterized by precipitable water values at or above 
1.75 inches...is expected to continue to advect northeastward...from 
the western Gulf Coast and Southern Plains through much of the lower 
half of the Mississippi Valley. 

The impact of the remnants of the ongoing convection...which 
probably will linger this morning across a considerable portion of 
the lower southern and Central Plains into lower Missouri 
Valley...on convective potential for later today remain unclear. 
But the various models do indicate that at least one significant 
short wave impulse will accelerate north northeastward...from the 
Texas South Plains at 12z this morning...through the middle/lower 
Missouri Valley by 12z Monday. As this occurs...guidance is 
generally suggestive that southerly Lower/Middle tropospheric flow will 
strengthen to 30-50+ knots within a belt overspreading the southeastern 
plains and lower half of the Mississippi Valley by late tonight. 

..southeastern plains into the middle Mississippi Valley... 
The eastern/leading edge of conglomerate convective outflow 
currently is expected to extend from parts of the Missouri Ozarks 
southward through far eastern Oklahoma and eastern Texas at 12z this 
morning. Ahead of this boundary...despite relatively weak middle-level 
lapse rates...low-level moistening /upper 60s to around 70f dew 
points/ and insolation are expected to contribute to at least modest 
cape /1000-2000 j per kg/. In the presence of strengthening 
Lower/Middle tropospheric flow...the environment probably will become 
conducive to the evolution of organized storm clusters. Discrete 
supercells also appear possible...with the risk for a couple of 
tornadoes...in addition to damaging wind gusts...as activity spreads 
northeastward from the arklatex vicinity through the Ozark Plateau 
during the afternoon and evening hours. One or two strong tornadoes 
may not be out of the question. 

..Central High pains into Southern Plains... 
Models suggest moderate boundary layer destabilization is possible 
beneath steeper middle-level lapse rates...along the dryline...from the 
Central High plains and Texas/Oklahoma Panhandle region into central 
Texas. This will provide an environment potentially conducive to 
strong/severe storm development...though vertical shear and 
middle/upper support for convection...in the wake of the short wave 
impulse expected to be migrating across the lower Central Plains 
during peak heating...is more unclear. At least a window of 
opportunity appears to exist for isolated to widely scattered 
strong/severe storm development late this afternoon and 
evening...particularly across the Panhandle region. 

.Kerr/picca.. 05/24/2015 

Mesoscale Discussion

acus11 kwns 240817 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 240816 

Mesoscale discussion 0738 
National Weather Service Storm Prediction Center Norman OK 
0316 am CDT sun may 24 2015 

Areas affected...N-cntrl Texas...southeastern OK 

Concerning...Tornado Watch 199...200... 

Valid 240816z - 240915z 

The severe weather threat for Tornado Watch 199...200...continues. 

Summary...ww/S 199/200 are scheduled to expire at 09z. Replacement 
ww issuance is unlikely...but local temporal extension is possible 
with a risk for strong wind gusts and perhaps a brief/weak tornado 
in association with an mesoscale convective vortex evolving north-northeast from the metroplex. 

Discussion...mesoscale convective vortex over the northern portion of the metroplex currently is 
moving north around 40 knots along the I-35 corridor. Larger-scale 
convective outflow boundary is evident in 08z surface analysis from 
Marshall to Adair County OK. It appears plausible that this mesoscale convective vortex 
should continue its northward track towards the Red River before shifting 
more northeasterly over southeastern OK. Given recent measured wind gusts to near 40 
knots in the past hour /kdal and krbd/...these may be capable of 
isolated damage. With warm sector air over northestern Texas/southeastern OK 
characterized by lower 70s surface temperatures and near 70 dew 
points...transient/weak mesovortices will remain 
possible...especially as the mesoscale convective vortex interacts with the larger-scale 
outflow boundary. 

.Grams.. 05/24/2015 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 33219692 33799673 34339591 35019505 35549468 35649452 
35439441 35009445 34219476 33719575 33039637 32889668 
33029686 33219692